you should add more eevee evolutions and branch them off this will make eevee the main pokemon to keep no matter what as it can become anything you want also will add pokemon for elite four to use while decreasing the number of pokemon most people hated to see and will give the game its very own feel to it so instead of a simple starter it makes it into the best pokemon obtainable

ex:

normal > psychic > dark or ghost (stone/time of day)

normal > grass > poison or bug (stone/ happyness or location if you want to get really into the scripting)